1. Field of the Invention
This invention relates to polymeric conductive films and to plastic solids and to electrochemical methods for forming such conductive polymers as films on plastic parts. This invention relates to in-mold coating techniques. More specifically it relates to a novel in-mold electrodeposition process which enables the deposition of conductive polymers as films on a catalyst-treated mold surface and the subsequent in-mold transfer of said film to a molded part to yield, for example, static free molded plastic parts.
2. Description of Prior Art
Various conductive polymeric organic solids are known such as for example, polyacetylene doped with As or Sb flourides or other rare earth salts; poly-p-phenylene doped with I.sub.2 ; polythiophene; and polypyrrole.
Bargon, J., Mohmond, S., and Waltman, R. J., IBM J. Res. Develop., 27, No. 4, 330-41 (1983) describes the electrochemical synthesis of a variety of electrically conducting polymers from aromatic compounds.
Soga, K., et al., Synthetic Materials, 6 275-83 (1983) describes moderately conductive, predominantly globular, polymers prepared by dehydrohalogenation of PVC.
Yoshino, K., et al., Japanese J. Applied Physics, 22, No. 6 L 376-78 (1983) describes enhanced conductivity for polyacetylene systems by electron beam irradiation in the presence of dopants, such as SF6 and C.sub.2 H.sub.2.
Electrochemical methods have been used to generate conducting organic polymers as free standing films. In particular, electropolymerization of pyrrole, N-substituted pyrrole derivatives, thiophene and substituted thiophene has been reported. These free standing thin films, while interesting, have not been widely used due to their fragility inherent in their thinness. The present invention advances the state of the art by providing a rapid method for providing practical plastic substrates coated with these conductive polymers thus making these polymers commercially useful.
The electrical conductivity of polymeric conductive organic solids and films it is believed can vary from semiconductor to metallic conductivities. These conductive polymeric solids if formed as films of conductive coatings onto plastic parts can yield static free plastic parts. The present invention could be used to form a conductive layer on molded plastic parts to dissipate static buildup to thus minimize the risk of sparks anywhere near explosive gases or mixtures. Moreover, to the extent conductivity of the conductive organic film can be controlled, further applications could include batteries, p-n junctions, EMI shields, photoconductors, chemical sensors, microwave absorbers, superconductors, circuits, and a variety of switches. Many of these applications could be realized by a successful electrodeposited in-mold coating production process to manufacture plastic parts having conductive or semi-conductive polymeric coatings. Such an electrodeposited in-mold coating process is disclosed by the present invention.